Change an old source driver to the network() driver

Replace the driver with network. For example, replace udp( with network(

Set the transport protocol.

If you used TLS-encryption, add the transport("tls") option, then continue with the next step.

If you used the tcp or tcp6 driver, add the transport("tcp") option.

If you used the udp or udp driver, add the transport("udp") option.

If you use IPv6 (that is, the udp6 or tcp6 driver), add the ip-protocol(6) option.

If you did not specify the port used in the old driver, check network() source options and verify that your clients send the messages to the default port of the transport protocol you use. Otherwise, set the appropriate port number in your source using the port() option.

All other options are identical. Test your configuration with the syslog-ng --syntax-only command.

Replace the driver with network. For example, replace udp( with network(

Set the transport protocol.

If you used TLS-encryption, add the transport("tls") option, then continue with the next step.

If you used the tcp or tcp6 driver, add the transport("tcp") option.

If you used the udp or udp driver, add the transport("udp") option.

If you use IPv6 (that is, the udp6 or tcp6 driver), add the ip-protocol(6) option.

If you did not specify the port used in the old driver, check network() source options and verify that your clients send the messages to the default port of the transport protocol you use. Otherwise, set the appropriate port number in your source using the port() option.

All other options are identical. Test your configuration with the syslog-ng --syntax-only command.

udp-balancer: Receiving UDP messages at very high rate

The udp-balancer() source allows you to use multiple CPU cores to process the incoming UDP messages at a very high message rate, depending on the available hardware resources, incoming message size, and your syslog-ng PE configuration. Note that this feature requires a Linux kernel that supports the SO_REUSEPORT kernel option, so it is supported only selected platforms.

The udp-balancer() source uses multiple CPU cores that listen on a single UDP port. This allows the source to scale to very high message rates. Using a single port is convenient, because you do not need to use load balancing on the client side. You can set the number of listeners using the listeners() option. For the best performance, the value of the listeners() option should be equal to the number of cores available on the host running syslog-ng PE.

When to use the udp-balancer() source

One Identity recommends using the udp-balancer() source if all of the following apply:

You are running syslog-ng PE in relay or server mode on a platform that supports the udp-balancer() source. For details, see Limitations.

You must receive UDP message at a high message rate, and for some reason you cannot use TCP connections instead.

It is not critical for you to store the incoming messages in the order they were sent.

Limitations

The udp-balancer() source is using eBPF, therefore it works only with kernels that support eBPF. From the platforms supported by syslog-ng PE, the following meet this requirement with the listed (or newer) kernel:

Oracle Linux 7.7, kernel version 4.14.35

Red Hat Enterprise Linux 7 is NOT supported, because its kernel version is too old.

SUSE Linux Enterprise Server 12.4, kernel version 4.12.14

Ubuntu 18.04 LTS (Bionic Beaver), kernel version 4.15

Ubuntu 16.04 LTS (Xenial Xerus), kernel version 4.15

Since the udp-balancer() source is multithreaded, there is no way to guarantee that the destination of the log path will receive the messages in the same order as the clients sent them. If you need to maintain the original order of the messages, make sure that the log messages contain a unique identifier (for example, a message ID or timestamp), and that your log processor (for example, a SIEM) can use this ID to reorder the messages.

Declaration:

udp-balancer([options]);

By default, the udp-balancer() driver binds to 0.0.0.0, meaning that it listens on every available IPV4 interface on the UDP/514 port. To limit accepted connections to only one interface, use the localip() parameter. To listen on IPv6 addresses, use the ip-protocol(6) option.

udp-balancer() source options

encoding()

Type:

string

Default:

Description: Specifies the characterset (encoding, for example, UTF-8) of messages using the legacy BSD-syslog protocol. To list the available character sets on a host, execute the iconv -l command. For details on how encoding affects the size of the message, see Message size and encoding.

assume-utf8: The assume-utf8 flag assumes that the incoming messages are UTF-8 encoded, but does not verify the encoding. If you explicitly want to validate the UTF-8 encoding of the incoming message, use the validate-utf8 flag.

empty-lines: Use the empty-lines flag to keep the empty lines of the messages. By default, syslog-ng PE removes empty lines automatically.

expect-hostname: If the expect-hostname flag is enabled, syslog-ng PE will assume that the log message contains a hostname and parse the message accordingly. This is the default behavior for TCP sources. Note that pipe sources use the no-hostname flag by default.

kernel: The kernel flag makes the source default to the LOG_KERN | LOG_NOTICE priority if not specified otherwise.

no-hostname: Enable the no-hostname flag if the log message does not include the hostname of the sender host. That way syslog-ng PE assumes that the first part of the message header is ${PROGRAM} instead of ${HOST}. For example:

source s_dell {
network(
port(2000)
flags(no-hostname)
);
};

no-multi-line: The no-multi-line flag disables line-breaking in the messages: the entire message is converted to a single line. Note that this happens only if the underlying transport method actually supports multi-line messages. Currently the file() and pipe() drivers support multi-line messages.

no-parse: By default, syslog-ng PE parses incoming messages as syslog messages. The no-parse flag completely disables syslog message parsing and processes the complete line as the message part of a syslog message. The syslog-ng PE application will generate a new syslog header (timestamp, host, and so on) automatically and put the entire incoming message into the MESSAGE part of the syslog message (available using the ${MESSAGE} macro). This flag is useful for parsing messages not complying to the syslog format.

If you are using the flags(no-parse) option, then syslog message parsing is completely disabled, and the entire incoming message is treated as the ${MESSAGE} part of a syslog message. In this case, syslog-ng PE generates a new syslog header (timestamp, host, and so on) automatically. Note that since flags(no-parse) disables message parsing, it interferes with other flags, for example, disables flags(no-multi-line).

dont-store-legacy-msghdr: By default, syslog-ng stores the original incoming header of the log message. This is useful if the original format of a non-syslog-compliant message must be retained (syslog-ng automatically corrects minor header errors, for example, adds a whitespace before msg in the following message: Jan 22 10:06:11 host program:msg). If you do not want to store the original header of the message, enable the dont-store-legacy-msghdr flag.

sanitize-utf8: When using the sanitize-utf8 flag, syslog-ng PE converts non-UTF-8 input to an escaped form, which is valid UTF-8.

store-raw-message: Save the original message as received from the client in the ${RAWMSG} macro. You can forward this raw message in its original form to another syslog-ng node using the syslog-ng() destination, or to a SIEM system, ensuring that the SIEM can process it. Available only in 7.0.9 and later.

syslog-protocol: The syslog-protocol flag specifies that incoming messages are expected to be formatted according to the new IETF syslog protocol standard (RFC5424), but without the frame header. Note that this flag is not needed for the syslog driver, which handles only messages that have a frame header.

validate-utf8: The validate-utf8 flag enables encoding-verification for messages formatted according to the new IETF syslog standard (for details, see IETF-syslog messages). If theBOM1character is missing, but the message is otherwise UTF-8 compliant, syslog-ng automatically adds the BOM character to the message.

host-override()

Type:

string

Default:

Description: Replaces the ${HOST} part of the message with the parameter string.

ip() or localip()

Type:

string

Default:

0.0.0.0

Description: The IP address to bind to. By default, syslog-ng PE listens on every available interface. Note that this is not the address where messages are accepted from.

If you specify a multicast bind address and use the udp transport, syslog-ng PE automatically joins the necessary multicast group. TCP does not support multicasting.

ip-protocol()

Type:

number

Default:

4

Description: Determines the internet protocol version of the given driver (network() or syslog()). The possible values are 4 and 6, corresponding to IPv4 and IPv6. The default value is ip-protocol(4).

Note that listening on a port using IPv6 automatically means that you are also listening on that port using IPv4. That is, if you want to have receive messages on an IP-address/port pair using both IPv4 and IPv6, create a source that uses the ip-protocol(6). You cannot have two sources with the same IP-address/port pair, but with different ip-protocol() settings (it causes an Address already in use error).

For example, the following source receives messages on TCP, using the network() driver, on every available interface of the host on both IPv4 and IPv6.

ip-ttl()

keep-hostname()

If enabled (keep-hostname(yes)), syslog-ng PE assumes that the incoming log message was sent by the host specified in the HOST field of the message.

If disabled (keep-hostname(no)), syslog-ng PE rewrites the HOST field of the message, either to the IP address (if the use-dns() parameter is set to no), or to the hostname (if the use-dns() parameter is set to yes and the IP address can be resolved to a hostname) of the host sending the message to syslog-ng PE. For details on using name resolution in syslog-ng PE, see Using name resolution in syslog-ng.

NOTE:

If the log message does not contain a hostname in its HOST field, syslog-ng PE automatically adds a hostname to the message.

For messages received from the network, this hostname is the address of the host that sent the message (this means the address of the last hop if the message was transferred via a relay).

For messages received from the local host, syslog-ng PE adds the name of the host.

This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

NOTE:

When relaying messages, enable this option on the syslog-ng PE server and also on every relay, otherwise syslog-ng PE will treat incoming messages as if they were sent by the last relay.

keep-timestamp()

Type:

yes or no

Default:

yes

Description: Specifies whether syslog-ng should accept the timestamp received from the sending application or client. If disabled, the time of reception will be used instead. This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

Caution:

To use the S_ macros, the keep-timestamp() option must be enabled (this is the default behavior of syslog-ng PE).

listeners()

Type:

number

Default:

<number-of-processors-in-the-host>

The udp-balancer() source uses multiple CPU cores that listen on a single UDP port. This allows the source to scale to very high message rates. Using a single port is convenient, because you do not need to use load balancing on the client side. You can set the number of listeners using the listeners() option. For the best performance, the value of the listeners() option should be equal to the number of cores available on the host running syslog-ng PE.

log-fetch-limit()

Type:

number

Default:

10

Description: The maximum number of messages fetched from a source during a single poll loop. The destination queues might fill up before flow-control could stop reading if log-fetch-limit() is too high.

log-iw-size()

If the max-connections() option is set, the log-iw-size() will be divided by the number of connections, otherwise log-iw-size() is divided by 10 (the default value of the max-connections() option). The resulting number is the initial window size of each connection. For optimal performance when receiving messages from syslog-ng PE clients, make sure that the window size is larger than the flush-lines() option set in the destination of your clients.

Example: Initial window size of a connection

If log-iw-size(1000) and max-connections(10), then each connection will have an initial window size of 100.

log-msg-size()

Type:

number (bytes)

Default:

Use the global log-msg-size() option, which defaults to 65536.

Description: Maximum length of a message in bytes. This length includes the entire message (the data structure and individual fields). The maximal value that can be set is 268435456 bytes (256MB). For messages using the IETF-syslog message format (RFC5424), the maximal size of the value of an SDATA field is 64kB.

In most cases, it is not recommended to set log-msg-size() higher than 10 MiB.

max-connections()

Type:

number

Default:

10

Description: Specifies the maximum number of simultaneous connections.

pad-size()

Type:

number

Default:

0

Description: Specifies input padding. Some operating systems (such as HP-UX) pad all messages to block boundary. This option can be used to specify the block size. The syslog-ng PE application will pad reads from the associated device to the number of bytes set in pad-size(). Mostly used on HP-UX where /dev/log is a named pipe and every write is padded to 2048 bytes. If pad-size() was given and the incoming message does not fit into pad-size(), syslog-ng will not read anymore from this pipe and displays the following error message:

Padding was set, and couldn't read enough bytes

port() or localport()

Type:

number

Default:

514

Description: The port number to bind to.

program-override()

Type:

string

Default:

Description: Replaces the ${PROGRAM} part of the message with the parameter string. For example, to mark every message coming from the kernel, include the program-override("kernel") option in the source containing /proc/kmsg.

so-rcvbuf()

Type:

number

Default:

0

Description: Specifies the size of the socket receive buffer in bytes. For details, see the socket(7) manual page.

Caution:

When receiving messages using the UDP protocol, increase the size of the UDP receive buffer on the receiver host (that is, the syslog-ng PE server or relay receiving the messages). Note that on certain platforms, for example, on Red Hat Enterprise Linux 5, even low message load (~200 messages per second) can result in message loss, unless the so-rcvbuf() option of the source is increased. In this cases, you will need to increase the net.core.rmem_max parameter of the host (for example, to 1024000), but do not modify net.core.rmem_default parameter.

As a general rule, increase the so-rcvbuf() so that the buffer size in kilobytes is higher than the rate of incoming messages per second. For example, to receive 2000 messages per second, set the so-rcvbuf() at least to 2 097 152 bytes.

tags()

Type:

string

Default:

Description: Label the messages received from the source with custom tags. Tags must be unique, and enclosed between double quotes. When adding multiple tags, separate them with comma, for example, tags("dmz", "router"). This option is available only in syslog-ng 3.1 and later.

time-zone()

Type:

name of the timezone, or the timezone offset

Default:

Description: The default timezone for messages read from the source. Applies only if no timezone is specified within the message itself.

The timezone can be specified as using the name of the (for example, time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format (for example, +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.

trim-large-messages()

Type:

yes|no

Default:

Use the global trim-large-messages() option, which defaults to no.

Description: Determines what syslog-ng PE does with incoming log messages that are received using the IETF-syslog protocol using the syslog() driver, and are longer than the value of log-msg-size(). Other drivers ignore the trim-large-messages() option.

If set to no, syslog-ng PE drops the incoming log message.

If set to yes, syslog-ng PE trims the incoming log message to the size set in log-msg-size(), and adds the trimmed tag to the message. The rest of the message is dropped. You can use the tag to filter on such messages.

filter f_trimmed {
tags("trimmed");
};

If syslog-ng PE trims a log message, it sends a debug-level log message to its internal() source.

As a result of trimming, a parser could fail to parse the trimmed message. For example, a trimmed JSON or XML message will not be valid JSON or XML.

use-dns()

Type:

yes, no, persist_only

Default:

yes

Description: Enable or disable DNS usage. The persist_only option attempts to resolve hostnames locally from file (for example, from /etc/hosts). The syslog-ng PE application blocks on DNS queries, so enabling DNS may lead to a Denial of Service attack. To prevent DoS, protect your syslog-ng network endpoint with firewall rules, and make sure that all hosts which may get to syslog-ng are resolvable. This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

NOTE:

This option has no effect if the keep-hostname() option is enabled (keep-hostname(yes)) and the message contains a hostname.

use-fqdn()

Type:

yes or no

Default:

no

Description: Add Fully Qualified Domain Name instead of short hostname. This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

NOTE:

This option has no effect if the keep-hostname() option is enabled (keep-hostname(yes)) and the message contains a hostname.